This invention relates to an apparatus for transporting injection molded articles away from an injection molding machine on pallets which, after their removal from a pallet tower are loaded with the articles in a charging station in the region of the injection molding machine. Thereafter the loaded pallets are moved from the charging station back to the pallet tower which has an elevator that travels vertically along frame elements of the pallet tower and which may be freely movable, as needed, during the loading operation. The elevator supports transporting pallets, and one or more pallets may be coupled to a transporting pallet to form a transporting unit therewith. The elevator is adapted to receive at least two transporting units. The invention also relates to such transporting units formed of a transporting pallet and at least one pallet which is connected, as needed, with the transporting pallet and which may be disconnected from the transporting unit for charging the same with injection-molded articles produced by the injection molding machine.
In a known apparatus of the above-outlined type, as disclosed, for example, in U.S. Pat. No. 5,024,593 issued to Karl Hehl on Jun. 18, 1991, the articles discharged by the injection molding machine are placed in pallets which are situated in a charging station. These pallets are readied in a pallet tower in transporting units, and the empty pallets are taken from a transporting unit while the loaded pallets are added to another transporting unit. Each transporting unit comprises a transporting pallet on which a plurality of stackable pallets are interconnected to form a stacked unit. The loaded transporting units are transferred by a transferring device onto a linearly travelling transporting vehicle which moves parallel to the vertical symmetry plane of the injection molding machine. The transporting vehicle is furthermore so constructed that it is also able to support machine replacement parts in such a manner that simultaneously a container for the injection molded articles and an injection molding tool may be transported. For the removal of the pallets from the pallet tower and for the transfer of the loaded pallets into the pallet tower, however, a substantial and complex programming and structural arrangement are necessary since the pallets to be introduced into the charging station have to be separated by means of several vertical displacements of the elevator. This may cause undesired timing conflicts during the replacement of the pallets.
Further, JP-OS 57-184001 (Patent Abstracts of Japan, Volume 7, Issue 29 (M-191), 1174) and JP-OS 60-262776 (Patent Abstracts of Japan, Volume 10, Issue 142 (M-481), 2199) disclose transport carriages in which individual article containers are supported on support plates and in which injection molding tools are individually received in such a manner that they may be taken off for further processing by means of a horizontal movement. In either case, however, the supports for the injection-molded articles or, as the case may be, the tool components are situated at fixed, unchangeable distances which makes difficult an optimal utilization of the available conveying space as a function of the size of the injection-molded articles or, as the case may be, the injection tool components.
In the apparatus disclosed in the above-noted JP-OS 57-184001 reference, the article containers are pulled out of the transporting carriage by a hydraulic device and are thereafter continuously charged with the injection-molded articles supplied thereto. In order to effect such a continuous charging, underneath the supplied articles the article container is gradually pushed back into the transporting carriage so that during the charging operation the transporting carriage may not execute a free motion. As soon as the container is charged, a gate interrupts further supply of the injection-molded articles until the transporting carriage is displaced vertically, a new pallet is taken, and the latter has been moved into the initial position. Such a construction leads to undesired interruptions because, on the one hand, a continuous charging of the pallets, particularly when a removal device is used, is not possible and, on the other hand, during the replacement of the transporting carriage there is a significant delay until the new transporting carriage is again in a ready position.
U.S. Pat. No. 4,687,403, particularly as shown in FIGS. 2-5, discloses a substantially complex arrangement for taking individual pallets from a pallet stack by means of several vertical displacements of an elevator. In such a process the pallet stack is subdivided into two substacks so that from one substack the empty pallets are taken and after their charging they are added to the other substack. Upon consuming an entire pallet stack, the full pallet stack is pushed out of the apparatus and readied for transportation without the presence of corresponding transporting pallets.
JP-OS 63-1632 discloses a stacking device in which the stacked pallets are supported in an essentially two-dimensional carrier frame which is formed of two vertical frame elements connected to one another by a horizontal frame element.